Improved yields for semiconductor devices is an on-going goal. One area for improvement is process uniformity across the workpiece in the radial direction. In certain processes, the workpiece may receive more treatment near the workpiece center. For example, a deposition process may deposit more material near the center of a workpiece than near the outer edge of the workpiece. This may be due to the increased plasma density near the center of the deposition chamber.
As another example, a heated implant may provide a different dose near the outer edge, since the outer edge of the workpiece may be somewhat cooler than the rest of the workpiece. In yet another example, a spin coating process may leave more material near the outer edge of the workpiece, as compared to the workpiece center, due to the centripetal force pushing the coating toward the outer edge of the workpiece.
In these examples, process non-uniformity in the radial direction may negatively impact the yield of a semiconductor workpiece. In some cases, efforts are made to improve the uniformity of the process. Yet, there may be limits to the degree of uniformity achieved.
With respect to these and other considerations the present disclosure is provided.